Following convention we opt for a ResNet-50[1]} backbone and ResNet-18 models for the two hand streams. However note other more efficient backbones [2]} [3]} could be utilised for real time operation on edge devices. We also select a hand crop size of \(w_c = h_c = 224\)  and the random spatial crop \(C_s = 224\)  as this is the standard input size for a ResNet model, and simplifies equation REF  to \(\overline{w} = \overline{h} = \frac{S}{W}\) .
